I started editing in Wikipedia about 2 years ago, when I tried to find some info on a French bande-dessinée artist and the article was severly lacking. I added and corrected spelling here and there, got an account, cleaned up articles, joined a project, created stubs, added infoboxes and images, used templates, fixed layouts, removed spam and trivia, joined a wiki in another language, and than I just had to stop. I had a watchlist of over 400 articles, checked in almost every day. I had witnessed nasty ‘edit-wars’ and ‘ownership’ issues. People would get so worked up about this stuff, you’d think it was the most important thing in the world for them. And I was becoming one of them. It became too much of a hassle. So I’ve quit.
I still think wikipedia is great. It’s my primary source of info on the web. There are a lot of great people contributing. It was a lot of fun working with it too, I hope my list above is not putting anyone off. It’s not that hard to edit either, even if you’re a coding newbie. But please use your common sense and if you’re not sure about something, ask your questions on the talk pages, that’s what they’re for.